1. Field of the Invention
This invention relates generally to in-line fluid filter assemblies. More specifically, this invention relates to filter assemblies with a filter valve head that includes a shut-off means for automatically stopping fluid flow when the filter cartridge is removed.
2. Related Art
This invention has applications in many areas of fluid filtering, for example, water and beverage filtering in restaurants, homes, or food processing plants. Filtering may be required for removing bad tastes, odors, particulate, minerals, or even microbes, for example, to provide a consistent, high-quality beverage or food product or to meet purity standards for other down-stream processes.
Many filter cartridge plus head systems, herein called "filter assemblies", have been designed for in-line filtering of fluids. The filter cartridge is typically connected to a head that includes passages for directing the fluid into the filter cartridge from an upstream fluid conduit, such as a pipe or tube, and for directing the fluid out of the filter and into a downstream conduit. The head is often designed to be permanently installed into the fluid conduit by threaded couplings. The filter cartridge may itself be disposable or may include a reusable casing that encloses a disposable filter or that may be reloaded.
Several examples of in-line filter heads with internal shut-off valve systems are found in U.S. patents. Such patents include Pall (U.S. Pat. No. 3,040,894), Whiting (U.S. Pat. No. 3,283,907), Nicko (U.S. Pat. No. 3,715,032), Tauber (U.S. Pat. No. 4,199,443), and Posner (U.S. Pat. No. 5,108,598).
Pall discloses a filter system for removing suspended foreign matter from fluids. Upon removal of the filter bowl, a spring-biased valve sleeve drops down to close off the fluid inlet and outlet chambers. A lower, outer rim of the valve sleeve engages a sealing surface and elements to close a vertical inlet passage. A seal on the inner surface of the upper, narrow portion of the valve sleeve seals against a valve seat and bushing. The valve seat and bushing depend from a hollow, cylindrical wall, which has an outer surface that guides the inner surface of the valve sleeve and an inner surface that defines a vertical, tubular fluid outlet chamber.
Whiting discloses a valve sleeve that is biased to move down when a filter is removed. The upper, horizontal rim of the valve sleeve seals against the horizontal top of an inwardly-extending protrusion to close off a vertical inlet passage. A lower, inside corner of the valve sleeve seals against a ledge or plate-shaped valve seat of a valve stop member. The valve stop member depends from a hollow, cylindrical wall, which has an outer surface that guides the inner surface of the valve sleeve and an inner surface that defines a vertical, tubular fluid outlet chamber.
Nicko discloses a spring-biased valve member that closes an outlet passage by pushing the valve member's bottom-end plug member against the top of a ring-shaped seat member mounted in the vertical, cylindrical outlet passage. To close off the inlet passage, an upper, cylindrical portion of the valve member seats against a cylindrical seat member formed in the vertical portion of the inlet passage.
Tauber discloses a spring-biased inner filter housing that drops down upon removal of the filter. The bottom edge of the inner filter housing seals against the bottom inside surface of the outer filter casing. The top flange of the inner filter housing seals against an inwardly-protruding rim to close off the outlet.
Posner discloses a filter cartridge with an inlet at one end of the filter cartridge and an outlet at the opposite end of the cartridge. Both the inlet and outlet ends are connected to fluid pipes via quick-connect couplers that include a 90.degree. angle, so that the cartridge may be removed horizontally from the pipes.
Filter valve systems that include two separate closure or valve members are disclosed in Walton, et al., (U.S. Pat. No. 2,431,782), and Humbert, Jr. (U.S. Pat. No. 2,894,630), Scavuzzo (U.S. Pat. No. 2,932,400), Southhall (U.S. Pat. No. 4,077,876), and Sikula, Jr. (U.S. Pat. No. 4,222,875).
Prior filter assemblies are too complicated, expensive, or difficult to maintain for many filtering applications. This is the case for the vending machine industry, for example, where large numbers of vending machines in a wide variety of settings must be maintained and kept in optimum condition. These vending machines require clean, filtered fluid to remove bad tastes, odors, hard water particles, etc. The filters used in these machines have a finite life and therefore often need to be replaced. Requirements for replacing the typical vending machine filter include the use of tools, technical knowledge of the product, and shutting off at least one valve in the fluid supply line before removal of the filter and reopening the valve(s) after installation of the filter.
Therefore, what is still needed is a user-friendly filter assembly that may be easily installed and replaced without the requirements of specific technical knowledge, tools, and manual valve operation. What is still needed is an improved auto-shut-off filter valve head design that is reliable, leak-proof, and economical.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved in-line filter assembly having a valve head with an automatic shut-off valve system. Another object of the invention is to simplify maintenance of the filter assembly, so that the cartridge may be easily and quickly removed and replaced without turning valves and using tools, and by someone not having detailed knowledge about the filtering flowscheme and apparatus. Another object is to provide an automatic shut-off system with negligible volume of residual liquid that might drip or flow out of the valve head when the cartridge is removed.
The present invention comprises a filter assembly having a valve head, herein also called a "valve head assembly", and a fluid filter cartridge. The valve head assembly is fixedly mounted in a fluid conduit, for support of the filter cartridge and for routing fluid to and from the filter cartridge through inlet and outlet passages that include an inlet port and an outlet port at the outer surface of the valve head assembly. The valve head assembly inner surface, which is formed by a piston sleeve, defines a centrally-located, vertically-aligned cylindrical bore for accepting and sealing the upper end of the said filter cartridge, so that the valve head inlet and outlet passages may be in fluid communication with the filter inlet and outlet openings. The filter cartridge cap is adapted to cooperate with the valve head, for starting and stopping fluid flow and for easy and secure attachment of the filter to the valve head.
The valve head assembly includes a valve or closure member, which automatically shuts-off and turns-on fluid flow and which is actuated by the removal and insertion of the filter cartridge, respectively. When the closure member is displaced to an open position by the filter cartridge being supported and sealed in the said valve head assembly, the inlet and outlet passages are opened or unblocked. When the closure member is biased to a closed position by the filter cartridge being unsupported and unsealed from said valve head assembly, the inlet and outlet passages are closed or blocked.
Preferably, the closure member is a single, generally cylindrical, hollow, open-ended, piston member with an interior space for receiving a stem member. When the piston is raised by the insertion of the filter cartridge, the piston slides up further into the cylindrical bore, guided on its exterior surface by the surface of the piston sleeve. As it slides up, the piston exposes radial openings in the piston sleeve, and, also, exposes a fluid exit hole or channel in the stem member. The radial openings allow fluid to flow from the inlet port, through the piston sleeve and into the cylindrical bore to reach the filter inlet. The exit hole or channel in the stem member allows filtered fluid to flow from the filter outlet and up through a space between the interior of the piston and the central body of the stem member, so that fluid may reach the outlet port.
When the filter cartridge is lowered, a biasing means pushes the piston downward and the piston vertical exterior surface seals against the piston sleeve vertical surface to block the radial openings. Also, the interior surface of the piston seals against the bottom end of the stem member, to block the space between the piston and stem member.
The preferred piston member, stem member, and biasing spring all touch each other and cooperate with each other, but are unattached to each other and unattached to the other elements of the valve head assembly. The piston member is supported inside the cylindrical bore of the valve head assembly, and the stem member is supported inside the piston member with its plate-shaped top abutting against the top surface of the cylindrical bore. The biasing spring extends between the piston and the stem and biases the piston and stem away from each other. Optionally, the stem member may be attached to the valve head but is not attached to the piston member.
The preferred filter cartridge has a cap with a centrally-located, upwardly-extending neck with vertical fluid inlet holes bored around the neck perimeter and a vertical fluid outlet hole bored in the center of the neck. An externally-threaded outer rim of the cap cooperates with the internal threads of the valve head to support the filter. A locking means is also provided between the valve head and filter cartridge.